import math
x_1,y_1,x_2,y_2 = map(float,input().split())
print(math.sqrt((x_1-x_2)**2+(y_1-y_2)**2)) import math math x_1,y_1,x_2,y_2 = map(float,input().split()) x_1 map(float,input().split()) map float input().split() ().split () input split y_1 x_2 y_2 print(math.sqrt((x_1-x_2)**2+(y_1-y_2)**2)) print math.sqrt((x_1-x_2)**2+(y_1-y_2)**2) math.sqrt math sqrt (x_1-x_2)**2+(y_1-y_2)**2 (x_1-x_2)**2 x_1-x_2 x_1 x_2 2 (y_1-y_2)**2 y_1-y_2 y_1 y_2 2 x_1,y_1,x_2,y_2 = map(float,input().split()) map(float,input().split()) x_1 y_1,x_2,y_2 = map(float,input().split()) map(float,input().split()) y_1 y_2 = map(float,input().split()) map(float,input().split()) y_2 x_2,y_2 = map(float,input().split()) map(float,input().split()) x_2
import math
x_1,y_1,x_2,y_2 = map(float,input().split())
print(math.sqrt((x_1-x_2)**2+(y_1-y_2)**2))
